/*
 * Copyright (C) 2020 Agrui
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.os;

import android.os.Handler;
import android.os.Message;
import java.lang.ref.WeakReference;

public class EventObserver {
    WeakReference   refH;
    int             what;
    Object          userObj;

    public EventObserver(Handler h, int what, Object obj) {
        refH = new WeakReference(h);
        this.what = what;
        userObj = obj;
    }

    public void notify(MessageData data) {
        Handler h = getHandler();

        if (h == null) {
            clear();
        } else {
            Message msg = Message.obtain();
            if (data.isInUse()) {
                throw new IllegalStateException(data + " This MessageData is already in use.");
            }

            data.markInUse();
            msg.what = what;
            msg.obj = data;
            h.sendMessage(msg);
        }
    }

    public void clear() {
        refH = null;
        userObj = null;
    }


    public Handler getHandler() {
        if (refH == null)
            return null;

        return (Handler) refH.get();
    }

}


